#!/usr/bin/python3
"""
Transforms the tree to an ostree layout
Creates a basic fs tree in OSTree layout[1] from scratch and then picks
the relevenat bits from the tree and moves them over.
Then uses `rpm-ostree compose` to transform a "normal" file system tree
into an OSTree conforming layout (see [1]). Among other things the main
steps are:
- moves /etc to /usr/etc
- move /boot to /usr/lib/ostree-boot
- potentially moving /var/lib/rpm
- re-creates the initramfs (via dracut)
- adds altfiles module to NSS
- Re-compiles SELinux policy (semodule -nB)
- Migrates /usr/etc/{passwd, group} to /usr/lib/
- Postprocess SELinux policy
- Convert /var to use tmpfiles.d
- Prepares symlinks
- /usr/local -> /var/usrlocal
- /var/lib/alternatives -> /usr/lib/alternatives
- /var/lib/vagrant -> /usr/lib/vagrant
- copies the rpmdb
The configuration options, `etc_group_members` corresponds to the
Treefile[2] option of rpm-ostree. In brief: The groups mentioned
in `etc_group_members` will be stored in /etc/groups instead of
/usr/etc/groups (which is read-only). Therefore all groups that
human users need to be part of.
[1] https://ostree.readthedocs.io/en/latest/manual/adapting-existing/
[2] https://rpm-ostree.readthedocs.io/en/latest/manual/treefile/
"""
import os
import subprocess
import sys
import tempfile
from osbuild import api
from osbuild.util import ostree
SCHEMA = """
"additionalProperties": false,
"properties": {
"etc_group_members": {
"description": "Array of group names to still keep in /etc/group",
"type": "array",
"items": { "type": "string" }
},
"initramfs-args": {
"description": "Array of arguments passed to dracut",
"type": "array",
"items": { "type": "string" }
},
"tmp-is-dir": {
"description": "Create a regular directory for /tmp",
"type": "boolean",
"default": true
}
}
"""
TOPLEVEL_DIRS = ["dev", "proc", "run", "sys", "sysroot", "var"]
TOPLEVEL_LINKS = {
"home": "var/home",
"media": "run/media",
"mnt": "var/mnt",
"opt": "var/opt",
"ostree": "sysroot/ostree",
"root": "var/roothome",
"srv": "var/srv",
}
def move(name, source, dest):
os.rename(os.path.join(source, name), os.path.join(dest, name))
def init_rootfs(root, tmp_is_dir):
"""Initialize a pristine root file-system"""
fd = os.open(root, os.O_DIRECTORY)
os.fchmod(fd, 0o755)
for d in TOPLEVEL_DIRS:
os.mkdir(d, mode=0o755, dir_fd=fd)
os.chmod(d, mode=0o755, dir_fd=fd)
for l, t in TOPLEVEL_LINKS.items():
# <dir_fd>/l -> t
os.symlink(t, l, dir_fd=fd)
if tmp_is_dir:
os.mkdir("tmp", mode=0o1777, dir_fd=fd)
os.chmod("tmp", mode=0o1777, dir_fd=fd)
else:
os.symlink("tmp", "sysroot/tmp", dir_fd=fd)
def main(tree, options):
etc_group_members = options.get("etc_group_members", [])
initramfs = options.get("initramfs-args", [])
tmp_is_dir = options.get("tmp-is-dir", True)
# rpm-ostree will either ensure that machine-id is empty
# when machineid-compat is 'true' is or will remove it
# otherwise. Since we have to decide, detect the current
# state and make rpm-ostree follow suit
machineid_compat = os.path.exists(f"{tree}/etc/machine-id")
print(f"ostree: machineid-compat: {machineid_compat}")
# Move /etc to /usr
os.rename(f"{tree}/etc", f"{tree}/usr/etc")
# NB: need to create the temporary direct at the same
# device as the tree is located on, so we can rename(2);
# since tree is a bind mount, it basically means it
# needs to be at the root of tree. So do that and then
# filter that directory out when moving stuff
with tempfile.TemporaryDirectory(dir=tree) as root:
print("Moving tree to temporary root")
for entry in os.scandir(tree):
if entry.path == root:
continue
dest = os.path.join(root, entry.name)
os.rename(entry.path, dest)
print("Initializing new root filesystem")
init_rootfs(tree, tmp_is_dir)
print("Moving data back from temporary root")
move("usr", root, tree)
move("boot", root, tree)
move("var", root, tree)
# move /home over to /var in case it is not empty
# rpm-ostree compose postprocess will convert the
# home dirs (and sub-dirs) to systemd-tmpfiles.
# NB: files and their content will not be converted
if any(os.scandir(f"{root}/home")):
move("home", root, f"{tree}/var")
for name in ["bin", "lib", "lib32", "lib64", "sbin"]:
if os.path.lexists(f"{root}/{name}"):
move(name, root, tree)
treefile = ostree.Treefile()
treefile["boot-location"] = "new"
treefile["machineid-compat"] = machineid_compat
treefile["etc-group-members"] = etc_group_members
treefile["initramfs-args"] = initramfs
with treefile.as_tmp_file() as path:
subprocess.run(["rpm-ostree", "compose", "postprocess",
tree, path],
check=True)
if __name__ == '__main__':
args = api.arguments()
r = main(args["tree"], args["options"])
sys.exit(r)